In magnetic information recording devices, information is recorded on an information recording medium by using magnetic, optical or photomagnetic effects. A hard disk drive (referred to hereinbelow as HDD) device is a typical example of such devices.
Contemporary HDD devices are required to have a high capacity and a reduced diameter, and there is a strong demand for reducing the floating amount of a magnetic head and decreasing the unit recording area with the object of increasing the recording density. At the same time, ever more stringent requirements are placed on surface quality, such as surface roughness and fine waviness, which is required after polishing in the process for manufacturing glass substrates for HDD. This all means that enhanced polishing quality that can be compatible with a reduced amount of head floating.
Patent Document 1 describes an abrasive agent including abrasive grains constituted by high-purity cerium oxide in which the content ratio of cerium oxide in the total content of rare earth oxides is equal to or greater than 95% by mass in order to stabilize the polishing quality of HDD glass substrates.
In the field of semiconductors, more stringent requirements are also placed on surface smoothness of semiconductor wafers in response to a dramatic increase in the degree of integration and increase in capacity in recent years, and more accurate polishing techniques are required. For example, Patent Document 2 describes using an abrasive agent for a semiconductor wafer that includes high-purity cerium oxide abrasive grains since cerium oxide particles have a comparatively low hardness and are unlikely to penetrate into the surface to be polished.
Patent Document 1: Japanese Patent Application Publication No. 2001-89748
Patent Document 2: Japanese Patent Application Publication No. H10-106994